We have operated upon more than 130 children and young adults for congenital forms of left ventricular outflow tract obstruction. The present study involves the late results of these operations perfomed at our institution and a review of the published results from other institutions. Patients included in the study were aged 1-18 years old at operation who had been followed five or more years postoperatively. Forms of left ventricular outflow tract obstruction included valvular aortic stenosis, discrete and diffuse fibrous subaortic stenosis, and muscular subaortic stenosis. Operative mortalities were low (0-6%). However, the operations appear to be palliative ones because only approximately 50% of patients have satisfactory late results.